91 results on '"Konda Gokuldoss Prashanth"'
Search Results
2. Thermal deformation behavior and microstructural evolution of the rapidly-solidified Al–Zn–Mg–Cu alloy in hot isostatic pressing state
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Zhen Zhang, Hailong Cong, Zijuan Yin, Bo Qi, Yi Dong, Lingjun Kong, Haichao Li, and Konda Gokuldoss Prashanth
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Al–Zn–Mg–Cu alloy ,Hot isostatic pressing ,Constitutive model ,Processing map ,Microstructure evolution ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Isothermal uniaxial compression experiments were performed in the temperature range of 340–460 °C and the deformation rate range of 0.001–1 s−1 to analyze the hot deformation behavior of the rapidly-solidified Al–Zn–Mg–Cu alloy in hot isostatic pressing state. A strain-compensated constitutive model was established to determine the flow stress in the alloy (based on the true stress-true strain data), and the average activation energy for the hot deformation was calculated as Q = ∼146 kJ/mol. The proposed model exhibited a high predictability with an average absolute relative error of 2.68% and a correlation coefficient of 0.99724. The processing map revealed that the alloy in the hot isostatic pressed state offers better workability than the spray-deposited alloy, and its optimal workable ranges at a strain of 0.78 are 370–390 °C/0.004–0.01 s−1 and 400–460 °C/0.005–0.06 s−1, respectively. The microstructural evolution shows that the main dynamic softening mechanism changes from dynamic recovery to continuous dynamic recrystallization with the increase in temperature and the decrease in strain rate.
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- 2024
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3. High-temperature oxidation behaviors of Co-free Cr30Fe30Ni30Al5Ti5 dual-phase multi-component alloys with multi-scale nanoprecipitates
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Qingwei Gao, Yingying Wang, Jianhong Gong, Changshan Zhou, Jiyao Zhang, Xiaoming Liu, Junlei Tang, Pingping Liu, Xiangyan Chen, Dong Chen, Wenquan Lv, Konda Gokuldoss Prashanth, and Kaikai Song
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Multi-component alloys ,Microstructures ,Oxidation resistance ,Oxidation mechanism ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
In the context of the growing research interest in multi-component alloys (MAs) and their exceptional performance under extreme environments, the high-temperature oxidation resistance and applications of MAs have attracted significant attention in the field of metallic materials. While the cost-effective and mechanical properties of Co-free MAs are of great importance, their oxidation resistance remains insufficiently understood. In this work, we designed multiple heterogeneous structures within a cast dual-phase Cr30Fe30Ni30Al5Ti5 MA by tailoring the Al and Ti ratio, which consists of body-centered-cubic (BCC) grains reinforced by multi-scale nanoprecipitates (i.e., L21, B2, and η phase) and an L12-strengthened face-centered cubic (FCC) skeleton. Isothermal oxidation experiments at 800 °C, 1000 °C, and 1200 °C with varying exposure durations were conducted. The oxidation kinetics at 800 °C and 1000 °C followed a parabolic law, while both low weight increment and oxidation rate confirm remarkable oxidation resistance. At 800 °C, the oxides mainly consist of Cr2O3 and Al2O3, while are dominated by (TiO2 + Cr2O3) and the mixed oxides of Al2O3, TiO2, and Ti2O above 1000 °C. Importantly, the inability to form a continuous Al2O3 oxide scale at higher temperatures led to a deterioration in oxidation resistance. These findings offer valuable insights into underlying mechanisms contributing to oxidation resistance for Co-free MAs.
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- 2024
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4. Machine learning assisted design of high-entropy alloys with ultra-high microhardness and unexpected low density
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Shunli Zhao, Bin Jiang, Kaikai Song, Xiaoming Liu, Wenyu Wang, Dekun Si, Jilei Zhang, Xiangyan Chen, Changshan Zhou, Pingping Liu, Dong Chen, Zequn Zhang, Parthiban Ramasamy, Junlei Tang, Wenquan Lv, Konda Gokuldoss Prashanth, Daniel Şopu, and Jürgen Eckert
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High-entropy alloys ,Machine learning ,eXtreme Gradient Boosting ,Microhardness ,Microstructure ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
High-entropy alloys (HEAs) have attracted considerable attention for their exceptional microstructures and properties. Discovering new HEAs with desirable properties is crucial, but traditional design methods are laborious and time-consuming. Fortunately, the emerging Machine Learning (ML) offers an efficient solution. In this study, composition-microhardness data pairs from various alloy systems were collected and expanded using a Generative Adversarial Network (GAN). These data pairs were converted into empirical parameter-microhardness pairs. Then Active Learning (AL) was employed to screen the Al-Co-Cr-Cu-Fe-Ni system and identify the eXtreme Gradient Boosting (XGBoost) as the optimal ML master model. Millions of data training iterations employing the XGBoost sub-model and accuracy evaluations using the Expected Improvement (EI) algorithm establish the relationship between HEA compositions and microhardness. The proposed sub-model aligns well with experimental data, wherein four Al-rich compositions exhibit ultra-high microhardness (>740 HV, with a maximum of ∼780.3 HV) and low density (
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- 2024
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5. Selective laser melting of AlCoCrFeMnNi high entropy alloy: Effect of heat treatment
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Yacheng Fang, Pan Ma, Shuimiao Wei, Zhiyu Zhang, Dongye Yang, Hong Yang, Shiguang Wan, Konda Gokuldoss Prashanth, and Yandong Jia
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High entropy alloy ,Heat treatment ,Selective laser melting ,Microstructure ,Mechanical properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The dilemma concerning the trade-off between the strength and ductility of alloys has persistently been a significant problem in engineering applications. Conventional techniques such as grain refinement, severe plastic deformation, and precipitation strengthening usually increase strength at the expense of ductility. High entropy alloys with dual-phase structures, on the other hand, generally display excellent strength-ductility synergy. In this study, we attempted to mix pre-alloyed powders of two distinct phases (body-centered cubic - bcc and face-centered cubic - fcc) to fabricate AlCoCrFeMnNi HEAs with a dual-phase structure by selective laser melting. Furthermore, we investigate the impact of varying heat treatment temperatures (900 °C, 1000 °C, and 1100 °C) on its phase composition, microstructure, and mechanical properties. The results show that with an increase in the heat treatment temperature, the volume of the fcc phase increases gradually and the volume of the bcc phase decreases. The columnar structure in the fcc phase transforms into a cellular structure, and a spinodal decomposition is observed with the bcc phase. As the heat treatment temperature increases, the yield strength decreases while the elongation substantially increases, with the samples heat-treated at 1100 °C showing the best comprehensive properties (yield strength ∼700 MPa, tensile strength ∼950 MPa, and ∼15% ductility).
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- 2023
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6. Optimizing the Electrical Discharge Machining Process Parameters of the Nimonic C263 Superalloy: A Sustainable Approach
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Renu Kiran Shastri, Chinmaya Prasad Mohanty, Umakant Mishra, Tapano Kumar Hotta, Viraj Vishwas Patil, and Konda Gokuldoss Prashanth
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clean EDM ,Nimonic C263 ,neuro-genetic algorithm ,VIKOR index ,Production capacity. Manufacturing capacity ,T58.7-58.8 - Abstract
Engineers continue to be concerned about electrical discharge-machined components’ high energy consumption, machining debris, and poor dimensional precision. The aim of this research is to propose a hybrid neuro-genetic approach to improve the machinability of the electrical discharge machining (EDM) of the Nimonic C263 superalloy. This approach focuses on reducing the energy consumption and negative environmental impacts. The material removal rate (MRR), electrode wear ratio (EWR), specific energy consumption (SEC), surface roughness (Ra), machining debris (db), and circularity (C) are examined as a function of machining parameters such as the voltage (V), pulse on time (Ton), current (I), duty factor (τ), and electrode type. By employing the VIKOR method, all the responses are transformed into a distinctive VIKOR index (VI). Neuro-genetic methods (a hybrid VIKOR-based ANN-GA) can further enhance the best possible result from the VIKOR index. During this step, the hybrid technique (VIKOR-based ANN-GA) is used to estimate an overall improvement of 9.87% in the response, and an experiment is conducted to confirm this condition of optimal machining. This work is competent enough to provide aeroengineers with an energy-efficient, satisfying workplace by lowering the machining costs and increasing productivity.
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- 2024
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7. Microstructure and mechanical properties of AlCoCrFeMnNi HEAs fabricated by selective laser melting
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Pan Ma, Yacheng Fang, Shuimiao Wei, Zhiyu Zhang, Hong Yang, Shiguang Wan, Konda Gokuldoss Prashanth, and Yandong Jia
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Selective laser melting ,AlCoCrFeMnNi ,Microstructure ,Mechanical properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
To avoid the formation of cracks and to improve the forming capability and performance of the AlCoCrFeNi high entropy alloy (HEA), equiatomic CoCrFeNiMn HEA was added into equiatomic AlCoCrFeNi HEA to form a novel AlCoCrFeMnNi HEA. Three different compositions were prepared by the selective laser melting (SLM) technique, and their formability, microstructure, and mechanical properties were analyzed. Results revealed that AlCoCrFeMnNi shows a composite-like dual-phase structure composed of a soft FCC phase and hard BCC (A2/B2) phase. With the decrease of Al, the SLM forming capability is improved. Besides, the volume fraction of the phase and the nano-hardness decreases with decreasing Al content.
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- 2023
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8. NiTi–Cu Bimetallic Structure Fabrication through Wire Arc Additive Manufacturing
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Shalini Singh, Elena Demidova, Natalia Resnina, Sergey Belyaev, Palani Anand Iyamperumal, Christ Prakash Paul, and Konda Gokuldoss Prashanth
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structure ,shape memory alloys ,wire arc additive manufacturing ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
This study endeavors to comprehensively explore and elucidate the seamless integration of NiTi shape memory alloys (SMAs) into multifaceted applications through the utilization of novel joining techniques. The primary focus lies in the utilization of wire arc additive manufacturing (WAAM) to deposit Nitinol (NiTi) onto Copper (Cu), thereby introducing a transformative approach for their integration into electro-mechanical systems and beyond. Through a detailed examination of the NiTi/Cu bimetallic junction, using advanced analytical techniques including SEM, XRD, and DSC analyses, this research aims to unravel the intricate complexities inherent within the interface. The SEM images and X-ray patterns obtained reveal a complex and nuanced interface characterized by a broad mixed zone comprising various constituents, including Ti(Ni,Cu)2, pure Cu, Ti2(Ni,Cu)3 precipitates, and Ni-rich NiTi precipitates. The DSC results, showcasing low-intensity broad peaks during thermal cycling, underscore the inherent challenges in demonstrating functional properties within the NiTi/Cu system. Recognizing the critical importance of an enhanced martensitic transformation, this study delves into the effects of heat treatment. Calorimetric curves post-annealing at 500 °C exhibit distinct transformation peaks, shedding light on the intricate influence of NiTi layer distribution within the junction. The optimal heat treatment parameters for NiTi/Cu junction restoration are meticulously explored and determined at 500 °C for a duration of 12 h. Furthermore, the study offers valuable insights into optimizing NiTi–Cu joints, with micro-hardness values reaching 485 HV and compressive strength scaling up to 650 MPa. These significant findings not only hold promise for diverse applications across various industries but also pave the way for further research directions and explorations into the realm of SMA integration and advanced joining methodologies.
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- 2024
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9. ZrC+TiC synergically reinforced metal matrix composites with micro/nanoscale reinforcements prepared by laser powder bed fusion
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Lixia Xi, Lili Feng, Dongdong Gu, Ruiqi Wang, Baran Sarac, Konda Gokuldoss Prashanth, and Jürgen Eckert
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Laser powder bed fusion (LPBF) ,Aluminum matrix composites ,(ZrC+TiC) ceramic reinforcements ,Microstructure ,Properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The addition of hybrid ceramic reinforcing phases provides the possibility of regulating the in-situ reaction and effective strengthening in laser additive manufactured aluminum matrix composites (AMCs). In this work, AMCs reinforced with (ZrC + TiC) solid solution ceramics with micro/nanoscale microstructural features are fabricated by laser powder bed fusion (LPBF). The influence of laser power on the manufacturing quality, the microhardness and the wear properties of the LPBF-fabricated (ZrC + TiC)/Al composites is investigated. Moreover, the reaction mechanism between the ZrC and TiC ceramics in the LPBF process is revealed. The tensile properties of the (ZrC + TiC)/Al composites with different (ZrC + TiC) contents prepared at optimal process parameters are compared. During the LPBF process, the ZrC and TiC ceramics are incompletely melted. On the ceramic particles, a thin (Ti,Zr)C layer formed and large amounts of (Ti,Zr)C nanoparticles precipitated via a dissolution-precipitation mechanism. When the laser power increases from 375 to 425 W, the manufacturing quality, microhardness, tensile and wear properties of the (ZrC + TiC)/Al composites increase. The tensile strength of 10 wt.% (ZrC + TiC)/Al composites prepared at optimal processing parameters reaches a high strength value of ∼227 MPa with a uniform elongation of ∼6.7%, which is three times higher than that of the unreinforced Al-matrix. This is ascribed to the combined effects of Orowan strengthening, coefficient of thermal expansion (CTE) mismatch strengthening, load-bearing strengthening and grain refinement strengthening.
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- 2022
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10. Strong and ductile titanium via additive manufacturing under a reactive atmosphere
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Yangping Dong, Dawei Wang, Qizhen Li, Xiaoping Luo, Jian Zhang, Konda Gokuldoss Prashanth, Pei Wang, Jürgen Eckert, Lutz Mädler, Ilya V. Okulov, and Ming Yan
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Pure titanium ,Reactive atmosphere ,Additive manufacturing ,Laser powder bed fusion ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Pure metals tend to have a superior malleability compared to alloys. However, the applicability of pure metals is limited by their low strengths and hardness properties. In this study, strong and ductile pure Ti was synthesized via an approach involving powder modification and additive manufacturing (AM) under a reactive atmosphere. Specifically, pure Ti was processed by laser powder bed fusion in an environment containing a mixture of argon and nitrogen gases. In-situ high-energy synchrotron X-ray diffraction analysis reveals that in-situ nitrogen strengthening of the pure Ti occurs during the reactive AM of Ti. Furthermore, the presence of a nitrogen solid solution leads to the formation of high-strength pure Ti (yield strength of ∼979 MPa and ultimate tensile strength of ∼1058 MPa, respectively). This material exhibits excellent uniform elongation (11%) due to strong work hardening caused by the interaction of interstitial elements and submicrostructure. The proposed reactive AM approach paves the way for in-situ strengthening of pure metals and alloys.
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- 2023
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11. Selective Laser Melting and Spark Plasma Sintering: A Perspective on Functional Biomaterials
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Ramin Rahmani, Sérgio Ivan Lopes, and Konda Gokuldoss Prashanth
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functional biomaterials ,porous lattice structures ,laser powder bed fusion ,tissue engineering ,selective laser melting ,spark plasma sintering ,Biotechnology ,TP248.13-248.65 ,Medicine (General) ,R5-920 - Abstract
Achieving lightweight, high-strength, and biocompatible composites is a crucial objective in the field of tissue engineering. Intricate porous metallic structures, such as lattices, scaffolds, or triply periodic minimal surfaces (TPMSs), created via the selective laser melting (SLM) technique, are utilized as load-bearing matrices for filled ceramics. The primary metal alloys in this category are titanium-based Ti6Al4V and iron-based 316L, which can have either a uniform cell or a gradient structure. Well-known ceramics used in biomaterial applications include titanium dioxide (TiO2), zirconium dioxide (ZrO2), aluminum oxide (Al2O3), hydroxyapatite (HA), wollastonite (W), and tricalcium phosphate (TCP). To fill the structures fabricated by SLM, an appropriate ceramic is employed through the spark plasma sintering (SPS) method, making them suitable for in vitro or in vivo applications following minor post-processing. The combined SLM-SPS approach offers advantages, such as rapid design and prototyping, as well as assured densification and consolidation, although challenges persist in terms of large-scale structure and molding design. The individual or combined application of SLM and SPS processes can be implemented based on the specific requirements for fabricated sample size, shape complexity, densification, and mass productivity. This flexibility is a notable advantage offered by the combined processes of SLM and SPS. The present article provides an overview of metal–ceramic composites produced through SLM-SPS techniques. Mg-W-HA demonstrates promise for load-bearing biomedical applications, while Cu-TiO2-Ag exhibits potential for virucidal activities. Moreover, a functionally graded lattice (FGL) structure, either in radial or longitudinal directions, offers enhanced advantages by allowing adjustability and control over porosity, roughness, strength, and material proportions within the composite.
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- 2023
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12. Metallic Coatings through Additive Manufacturing: A Review
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Shalini Mohanty and Konda Gokuldoss Prashanth
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additive manufacturing ,coatings ,metallic coating ,powder bed fusion ,direct energy deposition ,spray coating ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Metallic additive manufacturing is expeditiously gaining attention in advanced industries for manufacturing intricate structures for customized applications. However, the inadequate surface quality has inspired the inception of metallic coatings through additive manufacturing methods. This work presents a brief review of the different genres of metallic coatings adapted by industries through additive manufacturing technologies. The methodologies are classified according to the type of allied energies used in the process, such as direct energy deposition, binder jetting, powder bed fusion, hot spray coatings, sheet lamination, etc. Each method is described in detail and supported by relevant literature. The paper also includes the needs, applications, and challenges involved in each process.
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- 2023
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13. Cu-Ni-Sn alloy fabricated by melt spinning and selective laser melting: a comparative study on the microstructure and formation kinetics
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Chao Zhao, Zhi Wang, Daoxi Li, Lauri Kollo, Zongqiang Luo, Weiwen Zhang, and Konda Gokuldoss Prashanth
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Selective laser melting ,Melt spinning ,Rapid solidification ,Cu-15Ni-8Sn alloy ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Composition modification (elemental modification) is found to be an effective method for tuning the bimodal microstructure (equiaxed and column grains) observed in the selective laser melted (SLM) metallic materials, and thereby improving their properties. However, optimization for the powder composition is a tedious task consuming energy, time and resources. One of the non-equilibrium processes, melting spinning (MS), matches the solidification conditions of the SLM process (especially the cooling rate), which offers the possibility of using the MS process as the first step in optimizing the elements/alloy design and development for the SLM process. In this work, SLM and MS processes were employed to fabricate the Cu-Ni-Sn alloy to compare the microstructural features and the resultant properties. The result reveals that the sample fabricated by MS shows a similar supersaturated structure as the SLM counterpart and both these samples exhibit analogous microstructure consisting of fine equiaxed grains, column grains, intragranular and intergranular γ-(CuxNi1-x)3Sn phase. The results confirm the possibility of using the MS process as the first step in the alloy design/development for the SLM process.
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- 2020
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14. Editorial: Fundamentals and Challenges of Advanced Amorphous and High-Entropy Alloys
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Kaikai Song, Yongjiang Huang, Ran Li, Jichao Qiao, Zhi Wang, Konda Gokuldoss Prashanth, and Daniel Sopu
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amorphous alloys ,high-entropy alloys ,liquid structure ,mechanical properties ,deformation mechanism ,Technology - Published
- 2022
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15. Grain refinement in laser manufactured Al-based composites with TiB2 ceramic
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Lixia Xi, Dongdong Gu, Shuang Guo, Ruiqi Wang, Kai Ding, and Konda Gokuldoss Prashanth
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Al-based composites ,TiB2ceramic ,Selective laser melting (SLM) ,Grain refinement ,Mechanical property ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Al-based composites reinforced with TiB2 ceramics (1 wt.%, 2 wt.% and 5 wt.%) have been manufactured through selective laser melting (SLM). The results show that the densification, microstructure and mechanical properties of the SLM-processed composites are sensitive to the ceramic particle fraction. The average grain size of the composites decreased from ∼6.32 to ∼1.55 μm with increasing TiB2 fraction from 1 to 5 wt.% respectively. Fine equiaxed grains with narrow size distribution were obtained for composites with relatively high amount of TiB2 particles. The effects of TiB2 ceramic fraction on grain refinement and strengthening mechanisms of SLM-processed composites were discussed. Al-based composite with 2 wt.% TiB2 ceramic was determined to be optimum, especially in the view of manufacturing quality, grain refinement and mechanical properties. The composites at an optimum fraction of 2 wt.% TiB2 exhibited high microhardness of ∼127 HV0.2, tensile strength of ∼444 MPa, yield strength of ∼283 MPa and elongation of ∼4.2% owing to collective effects of dispersion and grain refinement strengthening as well as high degree of densification. This study can readily offer reference values for laser additive manufacturing of other metal matrix composites to obtain a good compromise of strength and ductility by tuning reinforcement fraction.
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- 2020
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16. Fiber Laser Welded Cobalt Super Alloy L605: Optimization of Weldability Characteristics
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B. Hari Prasad, G. Madhusudhan Reddy, Alok Kumar Das, and Konda Gokuldoss Prashanth
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fiber laser welding ,microstructure ,residual stress ,epitaxial growth ,fractography ,EBSD analysis ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The present study describes the laser welding of Co-based superalloy L605 (52Co-20Cr-10Ni-15W) equivalent to Haynes-25 or Stellite-25. The influence of laser welding process input parameters such as laser beam power and welding speed on mechanical and metallurgical properties of weld joints were investigated. Epitaxial grain growth and dendritic structures were visible in the weld zone. The phase analysis results indicate the formation of hard phases like CrFeNi, CoC, FeNi, and CFe in the weld zone. These hard phases are responsible for the increase in microhardness up to 321 HV0.1 in the weld zone, which is very close to the microhardness of the parent material. From the tensile strength tests, the ductile failure of welded specimens was confirmed due to the presence of dimples, inter-granular cleavage, and micro voids in the fracture zone. The maximum tensile residual stress along the weld line is 450 MPa, whereas the maximum compressive residual stress across the weld line is 500 MPa. On successful application of Response Surface methodology (RSM), laser power of 1448.5 W and welding speed of 600 mm/min i.e., line energy or heat input equal to 144 J/mm, were found to be optimum values for getting sound weld joint properties. The EBSD analysis reveals the elongated grain growth in the weld pool and very narrow grain growth in the heat-affected zone.
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- 2022
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17. Mechanical Properties and Microstructural Evolution of Ti-25Nb-6Zr Alloy Fabricated by Spark Plasma Sintering at Different Temperatures
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Qing Zhu, Peng Chen, Qiushuo Xiao, Fengxian Li, Jianhong Yi, Konda Gokuldoss Prashanth, and Jürgen Eckert
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Ti-Nb-Zr alloy ,spark plasma sintering ,powder metallurgy ,microstructure ,mechanical properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
High-energy ball milling and spark plasma sintering (SPS) are used to create high-strength Ti-25Nb-6Zr biomedical alloys with β structures. The Ti-25Nb-6Zr alloy microstructure and mechanical properties were examined as a function of the sintering temperatures. The results showed that as the sintering temperature was raised, the densification process was expedited, and the comprehensive mechanical characteristics increased at first, then dropped slightly. Moreover, under high temperatures, the fracture morphology of the Ti-25Nb-6Zr biomedical alloys exhibited more dimples, indicating enhanced plasticity of the material. Evaluating the mechanical properties of the Ti-25Nb-6Zr biomedical alloy sintered at 1623 K indicated a high compressive strength of 1678.4 ± 5 MPa and an elongation of 12.4 ± 0.5%. The strengthening mechanisms are discussed in terms of the formation and distribution of bcc-Ti in the matrix as well as the homogeneous distribution of Nb and Zr. This research presents a new method for fabricating Ti-25Nb-6Zr biomedical alloys with high strength and low modulus values. The theoretical grounds for the development of high-performance Ti-Nb-Zr alloys will be laid by detailed research of this technology and its strengthening mechanisms.
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- 2022
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18. Electroless Ni-P-MoS2-Al2O3 Composite Coating with Hard and Self-Lubricating Properties
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Shalini Mohanty, Naghma Jamal, Alok Kumar Das, and Konda Gokuldoss Prashanth
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electroless plating ,composite ,wettability ,microhardness ,lubricant ,coating ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The work aimed to produce Ni-P-MoS2-Al2O3 on Al-7075 alloys with multiple attributes through an electroless (EL) plating route. The effects of additives (MoS2 and Al2O3) in the EL bath on the surface morphology, topography, hardness, composition (phase and elemental), roughness, wettability, and coating thickness were evaluated. Results indicate a substantial enhancement in microhardness of the EL-coated surfaces by 70% (maximum hardness = ~316 HV) using powders, and 30% (244 HV) without powders. The maximum coating thickness and water contact angle obtained with powders were 6.16 μm and 100.46°, respectively. The coefficient of friction for the samples prepared using powders was 0.12, and for the base material it was 0.18. The compositional analysis through EDS and XRD suggested the incorporation of a hard and lubricious layer on the EL-coated surface owing to the presence of different phases of Al, Mo, P, Zn, O, and S. Therefore, the resulting coating surfaces impart hardness, self-lubrication, hydrophobicity, and wear resistance simultaneously.
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- 2022
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19. Microstructure, Mechanical Properties, and Corrosion Behavior of 06Cr15Ni4CuMo Processed by Using Selective Laser Melting
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Jayaraman Maya, Katakam Sivaprasad, Guttula Venkata Sarath Kumar, Rustam Baitimerov, Pavel Lykov, and Konda Gokuldoss Prashanth
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selective laser melting (SLM) ,microstructure ,mechanical properties ,corrosion ,Mining engineering. Metallurgy ,TN1-997 - Abstract
A new class of martensitic stainless steel, namely 06Cr15Ni4CuMo, with applications in marine engineering, was processed by using selective laser melting (SLM). A body-centered cubic martensitic microstructure was observed, and the microstructure was compared with wrought 410 martensitic stainless steel. The SLM-processed sample showed a hardness of 465 ± 10 HV0.5, which was nearly 115 HV0.5 less than the wrought counterpart. Similarly, the SLM-processed sample showed improved YS and UTS, compared with the wrought sample. However, reduced ductility was observed in the SLM-processed sample due to the presence of high dislocation density in these samples. In addition, 71% volume high-angle grain boundaries were observed, corroborating the high strength of the material. The corrosion behavior was investigated in seawater, and the corrosion resistance was found to be 0.025 mmpy for the SLM-processed 06Cr15Ni4CuMo steel and 0.030 mmpy for wrought 410 alloys, showing better corrosion resistance in the SLM-processed material.
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- 2022
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20. Effect of the Laser Processing Parameters on the Selective Laser Melting of TiC–Fe-Based Cermets
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Himanshu S. Maurya, Lauri Kollo, Marek Tarraste, Kristjan Juhani, Fjodor Sergejev, and Konda Gokuldoss Prashanth
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cermets ,additive manufacturing ,laser processing ,laser pulsing ,Production capacity. Manufacturing capacity ,T58.7-58.8 - Abstract
The influence of laser pulse shaping on the formation of TiC-Fe-based cermets with different laser process parameters is investigated. The impact of pulse shaping and laser melting peak power on the microstructural development and mechanical properties of SLM-built parts is addressed. This research focuses primarily on the process parameters required to produce crack-free components and includes investigations of mechanical properties such as microhardness and fracture toughness. To acquire optimal process parameters, samples were manufactured using pulse shaping technology with varying laser melting peak power and exposure time. The influence of laser melting peak power and pulse shape on microstructure development and phases was analyzed using a scanning electron microscope and X-ray diffraction.
- Published
- 2022
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21. Mechanical and Tribological Behavior of Gravity and Squeeze Cast Novel Al-Si Alloy
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Vadlamudi Srinivasa Chandra, Koorella S. V. B. R. Krishna, Manickam Ravi, Katakam Sivaprasad, Subramaniam Dhanasekaran, and Konda Gokuldoss Prashanth
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squeeze casting ,novel Al-Si alloy ,wear analysis ,microstructure ,mechanical properties ,pin on disc wear testing ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The automotive industry traditionally reduces weight primarily by value engineering and thickness optimization. However, both of these strategies have reached their limits. A 6% reduction in automotive truck mass results in a 13% improvement in freight mass. Aluminum alloys have lower weight, relatively high specific strength, and good corrosion resistance. Therefore, the present manuscript involves manufacturing Al-based alloy by squeeze casting. The effect of applied pressure during the squeeze cast and gravity cast of a novel Al-Si alloy on microstructural evolution, and mechanical and wear behavior was investigated. The results demonstrated that squeeze casting of the novel Al-Si alloy at high-pressure exhibits superior mechanical properties and enhanced wear resistance in comparison to the gravity die-cast (GDC) counterpart. Squeeze casting of this alloy, at high pressure, yields fine dendrites and reduced dendritic arm spacing, resulting in grain refinement. The finer dendrites and reduced dendritic arm spacing in high-pressure squeeze cast alloy than in the GDC alloy were due to enhanced cooling rates observed during the solidification process, as well as the applied squeeze pressure breaks the initial dendrites that started growing during the solidification process. Reduced casting defects in the high-pressure squeeze cast alloy led to a reduced coefficient of friction, resulting in improved wear resistance even at higher loads and higher operating temperatures. Our results demonstrated that squeeze casting of the novel Al-Si alloy at high-pressure exhibits a 47% increase in tensile strength, 33% increase in hardness, 10% reduction in coefficient of friction, and 15% reduction in wear loss compared to the GDC counterpart.
- Published
- 2022
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22. Evolution of Microstructure and Mechanical Properties of LM25–HEA Composite Processed through Stir Casting with a Bottom Pouring System
- Author
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Mekala Chinababu, Nandivelegu Naga Krishna, Katakam Sivaprasad, Konda Gokuldoss Prashanth, and Eluri Bhaskara Rao
- Subjects
metal matrix composite ,LM25 alloy ,stir casting ,high entropy alloy ,mechanical properties ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Aluminum matrix composites reinforced by CoCrFeMnNi high entropy alloy (HEA) particulates were fabricated using the stir casting process. The as-cast specimens were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results indicated that flake-like silicon particles and HEA particles were distributed uniformly in the aluminum matrix. TEM micrographs revealed the presence of both the matrix and reinforcement phases, and no intermetallic phases were formed at the interface of the matrix and reinforcement phases. The mechanical properties of hardness and tensile strength increased with an increase in the HEA content. The Al 6063–5 wt.% HEA composite had a ultimate tensile strength (UTS) of approximately 197 MPa with a reasonable ductility (around 4.05%). The LM25–5 wt.% HEA composite had a UTS of approximately 195 Mpa. However, the percent elongation decreased to roughly 3.80%. When the reinforcement content increased to 10 wt.% in the LM25 composite, the UTS reached 210 MPpa, and the elongation was confined to roughly 3.40%. The fracture morphology changed from dimple structures to cleavage planes on the fracture surface with HEA weight percentage enhancement. The LM25 alloy reinforced with HEA particles showed enhanced mechanical strength without a significant loss of ductility; this composite may find application in marine and ship building industries.
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- 2021
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- View/download PDF
23. A Review on Development of Bio-Inspired Implants Using 3D Printing
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Ansheed A. Raheem, Pearlin Hameed, Ruban Whenish, Renold S. Elsen, Aswin G, Amit Kumar Jaiswal, Konda Gokuldoss Prashanth, and Geetha Manivasagam
- Subjects
biomimetic ,additive manufacturing ,3D printing ,ceramics ,polymer ,metals ,Technology - Abstract
Biomimetics is an emerging field of science that adapts the working principles from nature to fine-tune the engineering design aspects to mimic biological structure and functions. The application mainly focuses on the development of medical implants for hard and soft tissue replacements. Additive manufacturing or 3D printing is an established processing norm with a superior resolution and control over process parameters than conventional methods and has allowed the incessant amalgamation of biomimetics into material manufacturing, thereby improving the adaptation of biomaterials and implants into the human body. The conventional manufacturing practices had design restrictions that prevented mimicking the natural architecture of human tissues into material manufacturing. However, with additive manufacturing, the material construction happens layer-by-layer over multiple axes simultaneously, thus enabling finer control over material placement, thereby overcoming the design challenge that prevented developing complex human architectures. This review substantiates the dexterity of additive manufacturing in utilizing biomimetics to 3D print ceramic, polymer, and metal implants with excellent resemblance to natural tissue. It also cites some clinical references of experimental and commercial approaches employing biomimetic 3D printing of implants.
- Published
- 2021
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24. Effect of Interlayer Delay on the Microstructure and Mechanical Properties of Wire Arc Additive Manufactured Wall Structures
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Shalini Singh, Arackal Narayanan Jinoop, Gorlea Thrinadh Ananthvenkata Tarun Kumar, Iyamperumal Anand Palani, Christ Prakash Paul, and Konda Gokuldoss Prashanth
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wire arc additive manufacturing ,interlayer delay ,characterization ,stainless steel 316L ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Wire arc additive manufacturing is a metal additive manufacturing technique that allows the fabrication of large size components at a high deposition rate. During wire arc additive manufacturing, multi-layer deposition results in heat accumulation, which raises the preheat temperature of the previously built layer. This causes process instabilities, resulting in deviations from the desired dimensions and variations in material properties. In the present study, a systematic investigation is carried out by varying the interlayer delay from 20 to 80 s during wire arc additive manufacturing deposition of the wall structure. The effect of the interlayer delay on the density, geometry, microstructure and mechanical properties is investigated. An improvement in density, reduction in wall width and wall height and grain refinement are observed with an increase in the interlayer delay. The grain refinement results in an improvement in the micro-hardness and compression strength of the wall structure. In order to understand the effect of interlayer delay on the temperature distribution, numerical simulation is carried out and it is observed that the preheat temperature reduced with an increase in interlayer delay resulting in variation in geometry, microstructure and mechanical properties. The study paves the direction for tailoring the properties of wire arc additive manufacturing-built wall structures by controlling the interlayer delay period.
- Published
- 2021
- Full Text
- View/download PDF
25. Annealing of Al-Zn-Mg-Cu Alloy at High Pressures: Evolution of Microstructure and the Corrosion Behavior
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Chuanjun Suo, Pan Ma, Yandong Jia, Xiao Liu, Xuerong Shi, Zhishui Yu, and Konda Gokuldoss Prashanth
- Subjects
high-pressure annealing ,Al-Zn-Mg-Cu alloy ,microstructure ,corrosion behavior ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Extruded Al-Zn-Mg-Cu alloy samples with grains aligned parallel to the extrusion direction were subjected to high-pressure annealing. The effects of annealing pressure on the microstructure, hardness, and corrosion properties (evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)) were investigated. Phase analysis showed the presence of MgZn2 and α-Al phases, the MgZn2 phase dissolved into the matrix, and its amount decreased with the increasing annealing pressure. The recrystallization was inhibited, and the grains were refined, leading to an increase in the Vickers hardness with increasing the annealing pressure. The corrosion resistance was improved after high-pressure treatment, and a stable passivation layer was observed. Meanwhile, the number of corrosion pits and the width of corrosion cracks decreased in the high-pressure annealed samples.
- Published
- 2021
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- View/download PDF
26. Phase Formation, Microstructure and Mechanical Properties of Mg67Ag33 as Potential Biomaterial
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Konrad Kosiba, Konda Gokuldoss Prashanth, and Sergio Scudino
- Subjects
Mg–Ag-based alloy ,metastable phase formation ,microstructure ,mechanical properties ,biomaterial ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The phase and microstructure formation as well as mechanical properties of the rapidly solidified Mg67Ag33 (at. %) alloy were investigated. Owing to kinetic constraints effective during rapid cooling, the formation of equilibrium phases is suppressed. Instead, the microstructure is mainly composed of oversaturated hexagonal closest packed Mg-based dendrites surrounded by a mixture of phases, as probed by X-ray diffraction, electron microscopy and energy dispersive X-ray spectroscopy. A possible non-equilibrium phase diagram is suggested. Mainly because of the fine-grained dendritic and interdendritic microstructure, the material shows appreciable mechanical properties, such as a compressive yield strength and Young’s modulus of 245 ± 5 MPa and 63 ± 2 GPa, respectively. Due to this low Young’s modulus, the Mg67Ag33 alloy has potential for usage as biomaterial and challenges ahead, such as biomechanical compatibility, biodegradability and antibacterial properties are outlined.
- Published
- 2021
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27. Effect of Substrate Plate Heating on the Microstructure and Properties of Selective Laser Melted Al-20Si-5Fe-3Cu-1Mg Alloy
- Author
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Pan Ma, Pengcheng Ji, Yandong Jia, Xuerong Shi, Zhishui Yu, and Konda Gokuldoss Prashanth
- Subjects
Al-Si-Fe-Cu-Mg alloy ,4XXX series ,selective laser melting ,heat treatment ,microstructure ,mechanical property ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The Al-20Si-5Fe-3Cu-1Mg alloy was fabricated using selective laser melting (SLM). The microstructure and properties of the as-prepared SLM, post-treated SLM, and SLM with substrate plate heating are studied. The as-prepared SLM sample shows a non-uniform microstructure with four different phases: fcc-αAl, eutectic Al-Si, Al2MgSi, and δ-Al4FeSi2. With thermal treatment, the phases become coarser and the δ-Al4FeSi2 phase transforms partially to β-Al5FeSi. The sample produced with SLM substrate plate heating shows a relatively uniform microstructure without a distinct difference between hatch overlaps and track cores. Room temperature compression test results show that an as-prepared SLM sample reaches a maximum strength (862 MPa) compared to the heat-treated (524 MPa) and substrate plate heated samples (474 MPa) due to the presence of fine microstructure and the internal stresses. The reduction in strength of the sample produced with substrate plate heating is due to the coarsening of the microstructure, but the plastic deformation shows an improvement (20%). The present observations suggest that substrate plate heating can be effectively employed not only to minimize the internal stresses (by impacting the cooling rate of the process) but can also be used to modulate the mechanical properties in a controlled fashion.
- Published
- 2021
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28. Selective Laser Melting of Aluminum and Its Alloys
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Zhi Wang, Raghunandan Ummethala, Neera Singh, Shengyang Tang, Challapalli Suryanarayana, Jürgen Eckert, and Konda Gokuldoss Prashanth
- Subjects
additive manufacturing ,selective laser melting ,light metals ,characterization ,properties ,applications ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The laser-based powder bed fusion (LBPF) process or commonly known as selective laser melting (SLM) has made significant progress since its inception. Initially, conventional materials like 316L, Ti6Al4V, and IN-718 were fabricated using the SLM process. However, it was inevitable to explore the possible fabrication of the second most popular structural material after Fe-based alloys/steel, the Al-based alloys by SLM. Al-based alloys exhibit some inherent difficulties due to the following factors: the presence of surface oxide layer, solidification cracking during melt cooling, high reflectivity from the surface, high thermal conductivity of the metal, poor flowability of the powder, low melting temperature, etc. Researchers have overcome these difficulties to successfully fabricate the different Al-based alloys by SLM. However, there exists no review dealing with the fabrication of different Al-based alloys by SLM, their fabrication issues, microstructure, and their correlation with properties in detail. Hence, the present review attempts to introduce the SLM process followed by a detailed discussion about the processing parameters that form the core of the alloy development process. This is followed by the current research status on the processing of Al-based alloys and microstructure evaluation (including defects, internal stresses, etc.), which are dealt with on the basis of individual Al-based series. The mechanical properties of these alloys are discussed in detail followed by the other important properties like tribological properties, fatigue properties, etc. Lastly, an outlook is given at the end of this review.
- Published
- 2020
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29. Vacuum Hot Pressing of Oxide Dispersion Strengthened Ferritic Stainless Steels: Effect of Al Addition on the Microstructure and Properties
- Author
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Dharmalingam Ganesan, Prabhukumar Sellamuthu, and Konda Gokuldoss Prashanth
- Subjects
ferritic ODS steel ,mechanical alloying ,vacuum hot pressing ,X-ray diffraction ,hardness ,Production capacity. Manufacturing capacity ,T58.7-58.8 - Abstract
The present article investigates the fabrication of oxide dispersion strengthened (ODS) ferritic stainless steel (FSS). Three different ODS alloys with three different Al contents were fabricated, where the presence of Al-based oxides play a crucial role in determining the size of the oxide particles. Due to Ostwald ripening, the samples with Al show coarser oxide particles compared to the alloy without Al, which hampers the density of the fabricated samples and, hence, have reduced hardness levels. The present results suggest that the composition of the oxide present in ODS plays a crucial role in determining the properties of these samples.
- Published
- 2020
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30. Selective Laser Melting: Materials and Applications
- Author
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Konda Gokuldoss Prashanth
- Subjects
n/a ,Production capacity. Manufacturing capacity ,T58.7-58.8 - Abstract
Additive manufacturing (AM) is one of the emerging manufacturing techniques of immense engineering and scientific importance and is regarded as the technique of the future [...]
- Published
- 2020
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31. Additive Manufacturing: Alloy Design and Process Innovations
- Author
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Konda Gokuldoss Prashanth and Zhi Wang
- Subjects
n/a ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Additive Manufacturing (AM) is an emerging manufacturing technique of immense engineering and scientific importance and is also regarded as the technique of the future [...]
- Published
- 2020
- Full Text
- View/download PDF
32. Effect of Milling Time and the Consolidation Process on the Properties of Al Matrix Composites Reinforced with Fe-Based Glassy Particles
- Author
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Özge Balcı, Konda Gokuldoss Prashanth, Sergio Scudino, Duygu Ağaoğulları, İsmail Duman, M. Lütfi Öveçoğlu, Volker Uhlenwinkel, and Jürgen Eckert
- Subjects
metallic glasses ,composites ,powder metallurgy ,mechanical characterization ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Al matrix composites reinforced with 40 vol% Fe50.1Co35.1Nb7.7B4.3Si2.8 glassy particles have been produced by powder metallurgy, and their microstructure and mechanical properties have been investigated in detail. Different processing routes (hot pressing and hot extrusion) are used in order to consolidate the composite powders. The homogeneous distribution of the glassy reinforcement in the Al matrix and the decrease of the particle size are obtained through ball milling. This has a positive effect on the hardness and strength of the composites. Mechanical tests show that the hardness of the hot pressed samples increases from 51–155 HV, and the strength rises from 220–630 MPa by extending the milling time from 1–50 h. The use of hot extrusion after hot pressing reduces both the strength and hardness of the composites: however, it enhances the plastic deformation significantly.
- Published
- 2015
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33. Selective Laser Melting of Ti-45Nb Alloy
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Holger Schwab, Konda Gokuldoss Prashanth, Lukas Löber, Uta Kühn, and Jürgen Eckert
- Subjects
selective laser melting ,Ti-45Nb ,additive manufacturing ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Ti-45Nb is one of the potential alloys that can be applied for biomedical applications as implants due to its low Young’s modulus. Ti-45Nb (wt.%) gas atomized powders were used to produce bulk samples by selective laser melting with three different parameter sets (energy inputs). A β-phase microstructure consisting of elliptical grains with an enriched edge of titanium was observed by scanning electron microscopy and X-ray diffraction studies. The mechanical properties of these samples were evaluated using hardness and compression tests, which suggested that the strength of the samples increases with increasing energy input within the range considered.
- Published
- 2015
- Full Text
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34. Mechanical Behavior of Ti6Al4V Scaffolds Filled with CaSiO3 for Implant Applications
- Author
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Ramin Rahmani, Maksim Antonov, Lauri Kollo, Yaroslav Holovenko, and Konda Gokuldoss Prashanth
- Subjects
Ti6Al4V scaffolds ,triply periodic minimal surfaces ,selective laser melting ,additive manufacturing ,biomaterial applications ,finite element analysis ,spark plasma sintering ,wollastonite ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Triply periodic minimal surfaces (TPMS) are becoming increasingly attractive due to their biomedical applications and ease of production using additive manufacturing techniques. In the present paper, the architecture of porous scaffolds was utilized to seek for the optimized cellular structure subjected to compression loading. The deformation and stress distribution of five lightweight scaffolds, namely: Rectangular, primitive, lattice, gyroid and honeycomb Ti6Al4V structures were studied. Comparison of finite element simulations and experimental compressive test results was performed to illustrate the failure mechanism of these scaffolds. The experimental compressive results corroborate reasonably with the finite element analyses. Results of this study can be used for bone implants, biomaterial scaffolds and antibacterial applications, produced from the Ti6Al4V scaffold built by a selective laser melting (SLM) method. In addition, Ti6Al4V manufactured metallic lattice was filled by wollastonite (CaSiO3) through spark plasma sintering (SPS) to illustrate the method for the production of a metallic-ceramic composite suitable for bone tissue engineering.
- Published
- 2019
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35. Microstructure and Mechanical Properties of Al–(12-20)Si Bi-Material Fabricated by Selective Laser Melting
- Author
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Shikai Zhang, Pan Ma, Yandong Jia, Zhishui Yu, Rathinavelu Sokkalingam, Xuerong Shi, Pengcheng Ji, Juergen Eckert, and Konda Gokuldoss Prashanth
- Subjects
Al–Si ,selective laser melting (SLM) ,microstructure ,mechanical properties ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
In this study, a combination of Al−12Si and Al−20Si (Al−(12-20)Si) alloys was fabricated by selective laser melting (SLM) as a result of increased component requirements such as geometrical complexity and high dimensional accuracy. The microstructure and mechanical properties of the SLM Al−(12-20)Si in as-produced as well as in heat-treated conditions were investigated. The Al−(12-20)Si interface was in the as-built condition and it gradually became blurry until it disappeared after heat treatment at 673 K for 6 h. This Al−(12-20)Si bi-material displayed excellent mechanical properties. The hardness of the Al−20Si alloy side was significantly higher than that of the Al−12Si alloy side and the disparity between both sides gradually decreased and tended to be consistent after heat treatment at 673 K for 6 h. The tensile strength and elongation of the Al−(12-20Si) bi-material lies in between the Al−12Si and Al−20Si alloys and fracture occurs in the Al−20Si side. The present results provide new insights into the fabrication of bi-materials using SLM.
- Published
- 2019
- Full Text
- View/download PDF
36. Superior Wear Resistance in EBM-Processed TC4 Alloy Compared with SLM and Forged Samples
- Author
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Weiwen Zhang, Peiting Qin, Zhi Wang, Chao Yang, Lauri Kollo, Dariusz Grzesiak, and Konda Gokuldoss Prashanth
- Subjects
Ti-6Al-4V ,wear ,additive manufacturing ,properties ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The wear properties of Ti-6Al-4V alloy have drawn great attention in both aerospace and biomedical fields. The present study examines the wear properties of Ti-6Al-4V alloy as prepared by selective laser melting (SLM), electron beam melting (EBM) and conventional forging processes. The SLM and EBM samples show better wear resistance than the forged sample, which correlates to their higher hardness values and weak delamination tendencies. The EBM sample shows a lower wear rate than the SLM sample because of the formation of multiple horizontal cracks in the SLM sample, which results in heavier delamination. The results suggest that additive manufacturing processes offer significantly wear-resistant Ti-6Al-4V specimens in comparison to their counterparts produced by forging.
- Published
- 2019
- Full Text
- View/download PDF
37. Production of Porous β-Type Ti–40Nb Alloy for Biomedical Applications: Comparison of Selective Laser Melting and Hot Pressing
- Author
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Ksenia Zhuravleva, Matthias Bönisch, Konda Gokuldoss Prashanth, Ute Hempel, Arne Helth, Thomas Gemming, Mariana Calin, Sergio Scudino, Ludwig Schultz, Jürgen Eckert, and Annett Gebert
- Subjects
novel β-phase Ti-based alloys ,static biomechanical behavior ,cytotoxicity and cell proliferation ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
We used selective laser melting (SLM) and hot pressing of mechanically-alloyed β-type Ti–40Nb powder to fabricate macroporous bulk specimens (solid cylinders). The total porosity, compressive strength, and compressive elastic modulus of the SLM-fabricated material were determined as 17% ± 1%, 968 ± 8 MPa, and 33 ± 2 GPa, respectively. The alloy’s elastic modulus is comparable to that of healthy cancellous bone. The comparable results for the hot-pressed material were 3% ± 2%, 1400 ± 19 MPa, and 77 ± 3 GPa. This difference in mechanical properties results from different porosity and phase composition of the two alloys. Both SLM-fabricated and hot-pressed cylinders demonstrated good in vitro biocompatibility. The presented results suggest that the SLM-fabricated alloy may be preferable to the hot-pressed alloy for biomedical applications, such as the manufacture of load-bearing metallic components for total joint replacements.
- Published
- 2013
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38. Influence of Powder Characteristics on Processability of AlSi12 Alloy Fabricated by Selective Laser Melting
- Author
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Rustam Baitimerov, Pavel Lykov, Dmitry Zherebtsov, Ludmila Radionova, Alexey Shultc, and Konda Gokuldoss Prashanth
- Subjects
additive manufacturing ,selective laser melting (SLM), AlSi12 alloy ,powder ,porosity ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Selective laser melting (SLM) is one of the additive manufacturing technologies that allows for the production of parts with complex shapes from either powder feedstock or from wires. Aluminum alloys have a great potential for use in SLM especially in automotive and aerospace fields. This paper studies the influence of starting powder characteristics on the processability of SLM fabricated AlSi12 alloy. Three different batches of gas atomized powders from different manufacturers were processed by SLM. The powders differ in particle size and its distribution, morphology and chemical composition. Cubic specimens (10 mm × 10 mm × 10 mm) were fabricated by SLM from the three different powder batches using optimized process parameters. The fabrication conditions were kept similar for the three powder batches. The influence of powder characteristics on porosity and microstructure of the obtained specimens were studied in detail. The SLM samples produced from the three different powder batches do not show any significant variations in their structural aspects. However, the microstructural aspects differ and the amount of porosity in these three specimens vary significantly. It shows that both the flowability of the powder and the apparent density have an influential role on the processability of AlSi12 SLM samples.
- Published
- 2018
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39. Influence of Nb on the Microstructure and Fracture Toughness of (Zr0.76Fe0.24)100−xNbx Nano-Eutectic Composites
- Author
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Tapabrata Maity, Anushree Dutta, Parijat Pallab Jana, Konda Gokuldoss Prashanth, Jürgen Eckert, and Jayanta Das
- Subjects
eutectic alloys ,microstructure ,mechanical properties ,indentation fracture toughness ,electron microscopy ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The present study demonstrates the evolution of eutectic microstructure in arc-melted (Zr0.76Fe0.24)100−xNbx (0 ≤ x ≤ 10 atom %) composites containing α-Zr//FeZr2 nano-lamellae phases along with pro-eutectic Zr-rich intermetallic phase. The effects of Nb addition on the microstructural evolution and mechanical properties under compression, bulk hardness, elastic modulus, and indentation fracture toughness (IFT) were investigated. The Zr–Fe–(Nb) eutectic composites (ECs) exhibited excellent fracture strength up to ~1800 MPa. Microstructural characterization revealed that the addition of Nb promotes the formation of intermetallic Zr54Fe37Nb9. The IFT (KIC) increases from 3.0 ± 0.5 MPa√m (x = 0) to 4.7 ± 1.0 MPa√m (x = 2) at 49 N, which even further increases from 5.1 ± 0.5 MPa√m (x = 0) and up to 5.9 ± 1.0 MPa√m (x = 2) at higher loads. The results suggest that mutual interaction between nano-lamellar α-Zr//FeZr2 phases is responsible for enhanced fracture resistance and high fracture strength.
- Published
- 2018
- Full Text
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40. Mechanical and Tribological Properties of Al2O3-TiC Composite Fabricated by Spark Plasma Sintering Process with Metallic (Ni, Nb) Binders
- Author
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Rohit Kumar, Anil K. Chaubey, Tapabrata Maity, and Konda Gokuldoss Prashanth
- Subjects
mechanical properties ,spark plasma sintering ,microstructure ,composites ,abrasion test ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Al2O3-10TiC composites were fabricated through the powder metallurgical process (mechanical milling combined with spark plasma sintering) with the addition of Ni/Nb as metallic binders. The effect of binder addition (Ni/Nb) on the processing, microstructure, and mechanical and tribological properties of the bulk-sintered composite samples was investigated. The microstructure of the composite reveals a homogeneous distribution of the TiC particles in the Al2O3 matrix. However, the presence of Ni/Nb was not traceable, owing to the small amounts of Ni/Nb addition. Hardness and density of the composite samples increase with the increasing addition of Nb (up to 2 wt. % Nb). Any further increase in the Nb content (3 wt. %) decreases both the hardness and the wear resistance. However, in case of Ni as binder, both the hardness and wear resistance increases with the increase in the Ni content from 1 wt. % to 3 wt. %. However, the composite samples with Nb as binder show improved hardness and wear resistance compared to the composites with Ni as binder.
- Published
- 2018
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41. Additive Manufacturing: Reproducibility of Metallic Parts
- Author
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Konda Gokuldoss Prashanth, Sergio Scudino, Riddhi P. Chatterjee, Omar O. Salman, and Jürgen Eckert
- Subjects
selective laser melting ,laser processing ,metals and alloys ,mechanical properties ,tensile properties ,Technology - Abstract
The present study deals with the properties of five different metals/alloys (Al-12Si, Cu-10Sn and 316L—face centered cubic structure, CoCrMo and commercially pure Ti (CP-Ti)—hexagonal closed packed structure) fabricated by selective laser melting. The room temperature tensile properties of Al-12Si samples show good consistency in results within the experimental errors. Similar reproducible results were observed for sliding wear and corrosion experiments. The other metal/alloy systems also show repeatable tensile properties, with the tensile curves overlapping until the yield point. The curves may then follow the same path or show a marginal deviation (~10 MPa) until they reach the ultimate tensile strength and a negligible difference in ductility levels (of ~0.3%) is observed between the samples. The results show that selective laser melting is a reliable fabrication method to produce metallic materials with consistent and reproducible properties.
- Published
- 2017
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42. Tensile Properties of Al-12Si Fabricated via Selective Laser Melting (SLM) at Different Temperatures
- Author
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Konda Gokuldoss Prashanth, Sergio Scudino, and Jürgen Eckert
- Subjects
selective laser melting ,light metals ,Al-based alloys ,mechanical properties ,Technology - Abstract
Additive manufacturing processes such as selective laser melting (SLM) are attracting increasing attention and are regarded as the manufacturing technology of the future, because of their ability to produce near net shaped components of theoretically any shape with added functionality. Various properties, including mechanical, tribological, welding, and corrosion properties, of Al-12Si alloys fabricated via SLM have been extensively studied. However, all of these studies were carried out at ambient conditions. Nevertheless, under working conditions, these alloys experience service temperatures ranging between 373 and 473 K. The present study focuses on the evaluation of the mechanical properties of SLM-fabricated Al-12Si alloys in this temperature range. For this, Al-12Si alloy specimens were annealed at 573 K, a temperature well beyond the test temperature in order to provide a stable microstructure during tensile testing. The plasticity of these materials increases along with the size of the dimples on the fracture surface with increasing tensile test temperature. Moreover, the annealed Al-12Si alloy exhibits appreciable tensile properties when tested between 373 K and 473 K. The results suggest that Al-12Si samples fabricated via SLM may be ideal candidates for automotive applications such as pistons and cylinder heads.
- Published
- 2016
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43. Characterization of 316L Steel Cellular Dodecahedron Structures Produced by Selective Laser Melting
- Author
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Konda Gokuldoss Prashanth, Lukas Löber, Hans-Jörg Klauss, Uta Kühn, and Jürgen Eckert
- Subjects
selective laser melting ,316L steel ,dodecahedron ,lattice structures ,compressive behavior ,Technology - Abstract
The compression behavior of different 316L steel cellular dodecahedron structures with different density values were studied. The 316L steel structures produced using the selective laser melting process has four different geometries: single unit cells with and without the addition of base plates beneath and on top, and sandwich structures with multiple unit cells with different unit cell sizes. The relation between the relative compressive strength and the relative density was compared using different Gibson-Ashby models and with other published reports. The different aspects of the deformation and the mechanical properties were evaluated and the deformation at distinct loading levels was recorded. Finite element method (FEM) simulations were carried out with the defined structures and the mechanical testing results were compared. The calculated theory, simulation estimation, and the observed experimental results are in good agreement.
- Published
- 2016
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44. Mechanical and Corrosion Behavior of New Generation Ti-45Nb Porous Alloys Implant Devices
- Author
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Konda Gokuldoss Prashanth, Ksenia Zhuravleva, Ilya Okulov, Mariana Calin, Jürgen Eckert, and Annett Gebert
- Subjects
titanium alloys ,sintering ,biomaterials ,porous materials ,corrosion ,Technology - Abstract
Strategies to improve the mechanical compatibility of Ti-based materials for hard tissue implant applications are directed towards significant stiffness reduction by means of the adjustment of suitable β-phases and porous device architectures. In the present study, the effect of different compaction routes of the gas-atomized β-Ti-45Nb powder on the sample architecture, porosity, and on resulting mechanical properties in compression was investigated. Green powder compacted and sintered at 1000 °C had a porosity varying between 8% and 12%, strength between 260 and 310 MPa, and Young’s modulus ranging between 18 and 21 GPa. Hot pressing of the powder without or with subsequent sintering resulted in microporosity varying between 1% and 3%, ultimate strength varying between 635 and 735 MPa, and Young’s modulus between 55 and 69 GPa. Samples produced with NaCl space-holder by hot-pressing resulted in a macroporosity of 45% and a high strength of ˃200 MPa, which is higher than the strength of a human cortical bone. Finally, the corrosion tests were carried out to prove that the presence of residual NaCl traces will not influence the performance of the porous implant in the human body.
- Published
- 2016
- Full Text
- View/download PDF
45. Microstructure and tribological behavior of Al–12Si – Nano graphene composite fabricated by laser metal deposition process
- Author
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Yang, Zhilu, Ma, Pan, Zhang, Nan, Yang, Dongye, Konda Gokuldoss, Prashanth, and Jia, Yandong
- Published
- 2023
- Full Text
- View/download PDF
46. Manufacturability and deformation studies on a novel metallic lattice structure fabricated by Selective Laser Melting
- Author
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Baskaran, Jagadeesh, Muthukannan, Duraiselvam, Shukla, Riddhi, and Konda Gokuldoss, Prashanth
- Published
- 2024
- Full Text
- View/download PDF
47. Evolution of Microstructure and Mechanical Properties of LM25–HEA Composite Processed through Stir Casting with a Bottom Pouring System
- Author
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Mekala Chinababu, Nandivelegu Naga Krishna, Katakam Sivaprasad, Konda Gokuldoss Prashanth, and Eluri Bhaskara Rao
- Subjects
Technology ,Microscopy ,QC120-168.85 ,QH201-278.5 ,mechanical properties ,Engineering (General). Civil engineering (General) ,Article ,stir casting ,TK1-9971 ,LM25 alloy ,Descriptive and experimental mechanics ,metal matrix composite ,high entropy alloy ,General Materials Science ,Electrical engineering. Electronics. Nuclear engineering ,TA1-2040 - Abstract
Aluminum matrix composites reinforced by CoCrFeMnNi high entropy alloy (HEA) particulates were fabricated using the stir casting process. The as-cast specimens were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results indicated that flake-like silicon particles and HEA particles were distributed uniformly in the aluminum matrix. TEM micrographs revealed the presence of both the matrix and reinforcement phases, and no intermetallic phases were formed at the interface of the matrix and reinforcement phases. The mechanical properties of hardness and tensile strength increased with an increase in the HEA content. The Al 6063–5 wt.% HEA composite had a ultimate tensile strength (UTS) of approximately 197 MPa with a reasonable ductility (around 4.05%). The LM25–5 wt.% HEA composite had a UTS of approximately 195 Mpa. However, the percent elongation decreased to roughly 3.80%. When the reinforcement content increased to 10 wt.% in the LM25 composite, the UTS reached 210 MPpa, and the elongation was confined to roughly 3.40%. The fracture morphology changed from dimple structures to cleavage planes on the fracture surface with HEA weight percentage enhancement. The LM25 alloy reinforced with HEA particles showed enhanced mechanical strength without a significant loss of ductility; this composite may find application in marine and ship building industries.
- Published
- 2022
48. Cu-Ni-Sn alloy fabricated by melt spinning and selective laser melting: a comparative study on the microstructure and formation kinetics
- Author
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Konda Gokuldoss Prashanth, Daoxi Li, Zongqiang Luo, Chao Zhao, Weiwen Zhang, Zhi Wang, and Lauri Kollo
- Subjects
Equiaxed crystals ,lcsh:TN1-997 ,Materials science ,Alloy ,02 engineering and technology ,engineering.material ,01 natural sciences ,Biomaterials ,Phase (matter) ,Cu-15Ni-8Sn alloy ,0103 physical sciences ,Selective laser melting ,Composite material ,Spinning ,Rapid solidification ,lcsh:Mining engineering. Metallurgy ,010302 applied physics ,Metals and Alloys ,Intergranular corrosion ,021001 nanoscience & nanotechnology ,Microstructure ,Surfaces, Coatings and Films ,Melt spinning ,Ceramics and Composites ,engineering ,0210 nano-technology - Abstract
Composition modification (elemental modification) is found to be an effective method for tuning the bimodal microstructure (equiaxed and column grains) observed in the selective laser melted (SLM) metallic materials, and thereby improving their properties. However, optimization for the powder composition is a tedious task consuming energy, time and resources. One of the non-equilibrium processes, melting spinning (MS), matches the solidification conditions of the SLM process (especially the cooling rate), which offers the possibility of using the MS process as the first step in optimizing the elements/alloy design and development for the SLM process. In this work, SLM and MS processes were employed to fabricate the Cu-Ni-Sn alloy to compare the microstructural features and the resultant properties. The result reveals that the sample fabricated by MS shows a similar supersaturated structure as the SLM counterpart and both these samples exhibit analogous microstructure consisting of fine equiaxed grains, column grains, intragranular and intergranular γ-(CuxNi1-x)3Sn phase. The results confirm the possibility of using the MS process as the first step in the alloy design/development for the SLM process.
- Published
- 2020
49. Selective Laser Melting of Aluminum and Its Alloys
- Author
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Konda Gokuldoss Prashanth, Jürgen Eckert, C. Suryanarayana, Zhi Wang, Raghunandan Ummethala, Shengyang Tang, and Neera Singh
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Materials science ,Fabrication ,applications ,Alloy ,chemistry.chemical_element ,02 engineering and technology ,Review ,engineering.material ,lcsh:Technology ,01 natural sciences ,Aluminium ,0103 physical sciences ,General Materials Science ,characterization ,Selective laser melting ,lcsh:Microscopy ,lcsh:QC120-168.85 ,light metals ,010302 applied physics ,Structural material ,lcsh:QH201-278.5 ,lcsh:T ,Metallurgy ,Titanium alloy ,021001 nanoscience & nanotechnology ,Microstructure ,Characterization (materials science) ,chemistry ,lcsh:TA1-2040 ,selective laser melting ,properties ,engineering ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:TK1-9971 ,additive manufacturing - Abstract
The laser-based powder bed fusion (LBPF) process or commonly known as selective laser melting (SLM) has made significant progress since its inception. Initially, conventional materials like 316L, Ti6Al4V, and IN-718 were fabricated using the SLM process. However, it was inevitable to explore the possible fabrication of the second most popular structural material after Fe-based alloys/steel, the Al-based alloys by SLM. Al-based alloys exhibit some inherent difficulties due to the following factors: the presence of surface oxide layer, solidification cracking during melt cooling, high reflectivity from the surface, high thermal conductivity of the metal, poor flowability of the powder, low melting temperature, etc. Researchers have overcome these difficulties to successfully fabricate the different Al-based alloys by SLM. However, there exists no review dealing with the fabrication of different Al-based alloys by SLM, their fabrication issues, microstructure, and their correlation with properties in detail. Hence, the present review attempts to introduce the SLM process followed by a detailed discussion about the processing parameters that form the core of the alloy development process. This is followed by the current research status on the processing of Al-based alloys and microstructure evaluation (including defects, internal stresses, etc.), which are dealt with on the basis of individual Al-based series. The mechanical properties of these alloys are discussed in detail followed by the other important properties like tribological properties, fatigue properties, etc. Lastly, an outlook is given at the end of this review.
- Published
- 2020
50. Vacuum Hot Pressing of Oxide Dispersion Strengthened Ferritic Stainless Steels: Effect of Al Addition on the Microstructure and Properties
- Author
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Konda Gokuldoss Prashanth, Dharmalingam Ganesan, and Prabhukumar Sellamuthu
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Ostwald ripening ,Materials science ,Fabrication ,Alloy ,Oxide ,02 engineering and technology ,engineering.material ,Hot pressing ,01 natural sciences ,Industrial and Manufacturing Engineering ,mechanical alloying ,symbols.namesake ,chemistry.chemical_compound ,0103 physical sciences ,010302 applied physics ,lcsh:T58.7-58.8 ,ferritic ODS steel ,Mechanical Engineering ,Metallurgy ,021001 nanoscience & nanotechnology ,Microstructure ,vacuum hot pressing ,hardness ,X-ray diffraction ,chemistry ,Mechanics of Materials ,X-ray crystallography ,symbols ,engineering ,0210 nano-technology ,Dispersion (chemistry) ,lcsh:Production capacity. Manufacturing capacity - Abstract
The present article investigates the fabrication of oxide dispersion strengthened (ODS) ferritic stainless steel (FSS). Three different ODS alloys with three different Al contents were fabricated, where the presence of Al-based oxides play a crucial role in determining the size of the oxide particles. Due to Ostwald ripening, the samples with Al show coarser oxide particles compared to the alloy without Al, which hampers the density of the fabricated samples and, hence, have reduced hardness levels. The present results suggest that the composition of the oxide present in ODS plays a crucial role in determining the properties of these samples.
- Published
- 2020
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